1. Field of the Invention
The present invention relates to an image pickup device capable of detecting the watching point of the operator and controlling the image pickup operation utilizing the detected information.
2. Related Background Art
In the field of cameras, there have been significant developments toward automated and diversified functions, and various functions such as automatic focusing and automatic exposure control are incorporated as standard, thus having resulted in a significant improvement in the operability.
These functions are attained by the information obtained from a detection area selected for example in the image frame. For example, in the automatic focusing, the focus state is detected from high frequency components in the image signal corresponding to the detection area, and the lens can be securely focused to the main object, utilizing thus a detected focus state.
More recently, for the purpose of further optimizing the control, there is proposed the use of a sight line detecting device which detects the watching point or the line of sight of the operator in the image frame of the view finder, and sets the detection area, for detecting the in,formation required in the abovementioned various functions, at a point watched by the operator, thereby reflecting the intention of said operator in the setting of the detection area. In this manner it is rendered possible to stably maintain the focused state to a constantly varying object, according to the intention of the operator, without errors such as eventual defocus under certain phototaking conditions or eventual focusing to an article other than the main object.
Such watched point detecting devices have been disclosed, for example, in U.S. Pat. Nos. 4,075,657, 4,109,145 and 4,574,314 and the Japanese Patent Laid-Open Application No. 61-172552.
However the watching point of the operator is not necessarily constant but is anticipated to fluctuate considerably. For this reason, if the defection area is simply set at the detected watching point, the setting position of the detection area becomes inadequate in case the watching point of the operator is displaced from the main object or is outside of the image frame of the view finder, so that the reliability of information obtained from said detection area and the accuracy of control are significantly deteriorated.
Also in the case where the operator executes an input operation for various functions in the course of a phototaking operation, such operation has to be conducted while the operator looks into the view finder, in order to confirm the switches or the like for such various functions, the operator has to shift his eye from the view finder, which will result in the danger of fluctuation of the image frame or of the main object being lost from the image frame. Such a drawback is becoming more serious with the increase in the functions of cameras or camcorders.
As a countermeasure for such drawback, there is conceived a camcorder in which the menu of various functions is displayed on the image frame of the monitoring view finder, then the operator watches a desired function, and a sight line detecting device detects the watching point of the operator whereby a function of which displayed menu is watched by the operator is executed. Such configuration allows the operator to easily effect the input operation for various functions without shifting the eye from the view finder.
Also in the functions assisting the phototaking operation, such as AF, AE, AWB or AS, it is possible to consider that the constantly moving main object is located at the watching position of the operator, to exactly detect said watching position by the sight line detecting device, and to move the detection area, tracking the movement of said watching point, thereby maintaining the moving object constantly in focus. In this manner the various functions can be attained more accurately, without contradicting the intention of the operator.
However, such control system utilizing the sight line detecting device for moving the detection area to the watching point of the operator, though functioning satisfactorily while the operator watches the desired object, will function based on erroneous information resulting from erroneous setting of the detection area if the watched point is positioned outside the image frame of the view finder or is in a position where the detection area cannot be practically set, thus leading to a deteriorated accuracy of control or eventually to an erroneous operation.